The invention relates to a vertebral body replacement implant having a bottom locating part for positioning against a lower vertebral body and having a top locating part for positioning against an upper vertebral body, wherein both locating parts are telescopically displaceable relative to one another in the manner of a piston-cylinder unit, having a sealed hydraulic chamber formed by the two locating parts, having a charging opening leading into the hydraulic chamber for a hydraulic medium, which upon entering the hydraulic chamber pushes the two locating parts apart from one another, and having a locking device, which may be activated by means of an instrument and upon activation fixes the two locating parts non-displaceably relative to one another.
Such a vertebral body replacement implant is described for example in US 2005/0060036 A1. This mode of construction makes it possible to adjust the spacing of the two locating parts in accordance with the spacing of the vertebral bodies that come into abutment on either side of the vertebral body replacement implant and then to fix the two locating parts relative to one another in the spacing adjusted by the hydraulic medium. After the fixing the hydraulic medium may be removed, the spacing of the two locating parts then being maintained exclusively by means of the locking device.
In the known vertebral body replacement implant, the charging opening for the hydraulic medium is disposed in the lower part of the one locating part, the fixing device in the upper part, so that in order to introduce the hydraulic medium, on the one hand, and actuate the locking device, on the other hand, a relatively large access is required because the appropriate instruments have to brought alongside one another towards the vertebral body replacement implant.
The object of the invention is to design a vertebral body replacement implant of the above general type in such a way that the handling, i.e. the filling with the hydraulic medium and the locking of the locking device, is possible through as small a body access as possible.